Radioactive source handling apparatus



March 3, 1964 F. MAUD ETAL 3,123,713

. RADIOACTIVE SOURCE HANDLING APPARATUS WITH SHOCK ABSORBING MEANS FOR HOLDING AND RELEASING RADIOACTIVE PELLETS Filed Sept. 25. 1960 g n! S Al SUPPLY PX/$4067 INV EN TORJ FAED MAUD THOMAS HOP/V E Mada/w AVTOIP/VEK United States Patent 3,123,713 RADIOACTIVE SOURCE HANDLING APPARATUS WlTI-I SHOCK ABSURBING MEANS FOR HOLD- ING AND RELEASING RADIOACTIVE PELLETS Fred Maud, Phiiadelphia, Pa., and Thomas Horne, Princeton, NJ., assignors, by mesne assignments, to The Budd Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Sept. 23, 1960, Ser. No. 58,125

7 Claims. (Cl. 250106) This invention relates to radioactive source handling apparatus for propelling and receiving radioactive sources and more particularly to a capturing and shock absorbing apparatus for receiving radioactive sources or other projectiles projected along a determined path, such as in a tube.

In such fields as industrial radiography, medical treatment, and food processing it is customary to propel radioactive sources back and forth between a shielded and unshielded position in a flexible unshielded tube. The higher the velocity of the source in traveling in the unshielded tube the better. There is less danger of exposure to radioactivity. However, the higher the velocity the greater the impact of the source when it slams into the receiving end. With higher velocities it also becomes more difficult to capture and hold the source in the desired position. There is a tendency for the source to bounce out of the holder or other supporting means at the receiving end.

Further, since this type of equipment is used for several thousands of cycles of operation the constant pounding of the source as it slams into the holder at the respective receiving end may result in serious damage to the source as well as the holder.

There is an even greater danger of rupturing the container in which the sources are sealed. If this occurs radioactive particles are strewn along the length of the tube contaminating it. These radioactive particles may even fall onto the object being treated resulting in further dangerous contamination.

Also, it is sometimes necessary to support the radioactive source in the proper position (horizontal, vertical, angular) at the receiving end. Thus it is necessary to provide means for positively holding the source at the receiving end.

Accordingly, it is an object of this invention to provide a radioactive source handling apparatus for propelling and capturing radioactive sources.

A further object of this invention is to provide a capturing and shock absorbing device for catching propelled radioactive sources.

Still another object of this invention is to provide a capturing and shock absorbing device for receiving and positively holding a propelled radioactive source.

Another object of this invention is to provide a means for removing the propelling force from a radioactive source when said radioactive source reaches the receiving position.

The present invention accomplishes these and many other objects and overcomes all of the disadvantages previously set forth. In its broadest aspect the invention may include means for propelling a radioactive source in a tube at a high velocity. A receiver arranged at the end of the tube includes shock absorbing means positioned in the path of travel of the source. The shock absorbing means comprises a movable electromagnet that is held against movement by a compression spring. When the source strikes the shock absorbing means a portion of it enters the electromagnet and moves it against the compression spring to actuate electrical means that energize the electromagnet, the compression spring absorbing the kinetic energy of the source. The resulting magnetic attraction between the source and the electromagnet posi tively holds the source in the receiver. The positive holding action of the electromagnet permits the source to be held in any position, vertical, horizontal or at an angle. Simultaneously with this action the propelling force is removed from the source until such time as it is desired to remove the source from the receiver. At that time the electromagnet may be deenergized and the source easily removed.

Other objects and advantages of our invention will be come apparent from the following description when taken in view of the accompanying drawings in which:

FIGURE 1 is a sectional View of our invention illustrating a radioactive source handling apparatus and including a source capturing and shock absorbing device and the control circuitry therefor.

FIGURE 2 is a sectional view of an alternative embodiment of the capturing and shock absorbing device shown in FIGURE 1.

Referring to FIG. 1 our invention comprises a flexible tube 11 that extends from a remote position not shown to a receiver 12where it is desired to place a radioactive source 13. Only a portion of the tube 1 1 is shown. The tube 11 is connected to a source of air pressure 14 through a two position, solenoid controlled air valve 16 at the remote position. When the solenoid control valve 16 is in a normal position, the tube 11 is connected to an exhaust port 17. p

The radioactive source 13 may comprise a sealed cobalt rod 18 encased in a flexible jacket 19. Enlarged end portions 21 and 22 formed of a dense shielding material such as a tungsten alloy are slidably received in the tube 11 so that when the solenoid control valve 16 is in an open position, the air pressure behind the radioactive source 1 3 will force it through the tube 11 at high speed. A probe 23 formed of magnetic material and having a rounded tip extends from the leading enlarged end portion 21 of the radioactive source 13. A trailing flexible strand 24 is secured to the other end portion 22 of the radioactive source 13. The strand 24 is used to withdraw the source from the receiver either manually or by motor driven take up means not shown. The radioactive source 13 may also be removed from the receiver 12 by pneumatic means if desired.

The receiver 12 comprises a hollow, cylindrical sleeve 26 which is flared or otherwise enlarged at one end 27 to receive and secure the end of the tube 17. The inner diameters of the tube 111 and sleeve 26 are the same so that there is a smooth, even union where they join. The sleeve 26 may be made of a dense shielding material such as lead or of a material easily penetrated by radioactive nays such as aluminum, stainless steel, etc. This depends on what position the receiver 12 is to be used, shielded or unshielded. The length of the sleeve 26 is chosen so that the source 1-3 completely fits therein. The end portions then effectively shield the ends of the sleeve.

A cylindrical, hollow casing 28 providing a chamber 29 is threadably secured to a flange 31 on the end of the sleeve 26. The chamber 29 slidably receives a cylindrical electromagnet 32 which is normally held against an end face 33 of the flange 31 by means of a compression spring 34 secured to an end face of the casing 28.

The electromagnet 32 comprises a spool 36 or reel of magnetic material with an electrical coil 37 wound thereon. A longitudinal bore 35 extends through the electromagnet. Electrical connectors 38 and 39 connected to the electromagnet 32. are brought out of the casing 28 through a longitudinal slot 41 formed in the casing. This permits the electromagnet 32 to move in the casing 28 against the compression spring '34 without damaging the electrical connections.

A switch actuator arm 42 extends through the sidewall of the casing 28 into the chamber at a selected distance from the rear end of the electromagnet 32 which is normally held against the end face 33 of the flange 31 by the compression spring 34. The distance between the switch actuator arm 42 and the rear end of the electromagnet 32 is determined by the size or strength of the compression spring 34- required to give the proper shock absorbing action when the source 13 slams into the receiver 12. This is in turn controlled by the weight and velocity or the kinetic energy of the source 13 when it reaches the receiver 12. Thus the size of the compression spring 34 employed and the spacing of the switch actuator arm 42 from the electromagnet 32 are variables which may be chosen so as to give the desired shock absorbing action.

When struck by the electromagnet 32 the switch actuator arm 42 operates a switch 43 suitably mounted in a protective housing 44 mounted adjacent to the chamber to complete a circuit between conductors 46 and 47. The conductors 38, 39, 46 and 47 are brought out of the housing 44 through a bushing 48 and formed into a cable 49.

The remainder of the electrical circuitry shown in H6. 1 can best be described by describing the operation of the apparatus. Assuming it is desired to propel the sealed radioactive source 13 in the tube 11 into the receiver 12 from a remote position, a manual control switch 51 connected by way of the conductor 46 to one side of a voltage source 52 is first closed. This connects a winding 53 of the solenoid control valve 16 across the voltage source 52 through a normally closed contact 54 of a relay 56. The relay 56 is connected to the voltage source 52 by the conductor 47. Energization of the winding 53 pulls an armature 57 of the solenoid control valve 16 to the left to open the solenoid control valve 16 and admit air under pressure from the air supply source 14 into the tube 11. With this, the radioactive source 13 is propelled through the tube 11 at a high velocity into the receiver 12.

The magnetic probe 23 enters the bore of the cylindrical electromagnet 32 as shown in FIG. 1 but the enlarged end 21 strikes the electromagnet 32 forcing it to move against the compression spring 34. After a predetermined amount of movement as can be controlled by the size of the compression spring 34 and the weight and velocity of the radioactive source 13, the cylindrical electromagnet 32 will strike the switch actuator arm 42 causing it to close the switch 43. Closing of the switch 43 momentarily completes an electrical circuit to energize the relay 56 by way of conductors 46 and 47 through the now closed switch 51. Energization of the relay 56 opens normally closed contact 54 to deenergize the winding 53 of the solenoid control valve 16. A compression spring 58 returns the solenoid control valve 16 to its former position allowing the air in the tube 11 to exhaust. This removes the propelling force from the source 13.

At the same time, the normally open contacts 59 and 6d of the relay 56 are closed to energize the electromagnet 32 by way of conductors 38 and 39, closed contacts 59 and the now closed switch 51. A signal lamp is also turned on. A holding circuit for the relay 56 is now completed through closed contacts 60 to keep the contacts 59 closed when the compression spring 34 returns the electromagnet to its normal position and the switch 43 is opened. This keeps the electromagnet 32 energized even though the switch 43 is open.

When the electromagnet 32 is energized the magnetic attraction between the probe 23 and the electromagnet 32 will positively hold the radioactive source 13 in the receiver 12. The signal lamp 5G is provided to indicate the presence of the source in the receiver.

When it is desired to release the radioactive source 13 from the receiver 12 and withdraw it, the switch 51 is opened. This will deenergize the relay 56, returning the closed contacts 59 to their normally open position and the now open contact 54 to its normally closed position. This in turn deenergizes the electromagnct 32 to release the probe 23. The radioactive source 13 may be withdrawn to its former position by the strand 24 either manually or by mechanical takeup means for instance. The radioactive source 13 can be removed from the receiver by pneumatic means as well as mechanical means by a suitable choice of valves and ports.

As the switch 51 is open the winding 53 0f the solenoid control valve 16 will remain deenergized and the solenoid control valve will remain in the closed position.

Referring now to FIG. 2 an alternative arrangement of the mechanical structure of a receiver is shown in an operating position. The electrical operation of this embodiment of the invention is the same as that previously described. In this arrangement a radioactive source is again provided with a magnetic probe 230. A cylindrical electromagnet 320 yieldably mounted within a casing 280 by means of a compression spring 340 is provided with a longitudinal bore 350, and a spring tensioned contact plunger 61 having a dished out end portion extends therein. The contact plunger 61 is provided with a shoulder 62 and extends through a compression plunger spring 63 and the end of the casing 230 into a housing 64 formed thereon. The compression spring 63 operates against the shoulder 62 to yieldably hold the contact plunger 61 in the bore 350 of the cylindrical electromagnet 329.

In operation the probe 230 of the radioactive source first strikes the contact plunger 61 forcing it against the plunger spring 63 and out of the bore 350 into the housing 64. As the contact plunger 61 is forced into the housing 64 it actuates a switch actuator arm 420 to momentarily close a switch 430. Closing of the switch 430 energizes the electromagnet 32d and returns the solenoid control valve 16 to its normal position as previously described. The energized electromagnct 320 will then hold the probe 23%) therein and support the radioactive source 130 in a desired position.

Thus, in this embodiment of the invention the shock of the impact of the source 130 in striking the receiver 120 is absorbed both by the compression spring 340 and the plunger spring 63. The electromagnet 320 when energized will catch and hold the source 130 in the desired position. By providing this positive shock absorbing and magnetic capturing action the radioactive source 130 will be positively held in the desired position without bounce or deflection and without damage to itself or to the receiver.

Although we have described our invention in detail it will be appreciated that many changes and modifications may be made by those skilled in the art without departing from the spirit of our invention which is to be limited only by the scope of the appended claims.

We claim:

1. A capturing and shock absorbing device for catching a projectile including a radioactive source that is projected through a tube into a receiving casing which comprises shock absorbing means positioned in the receiving casing in the path of said projectile for receiving and stopping said projectile at a position depending on the characteristics of the shock absorbing means and the kinetic energy of the projectile, electromagnetic capturing means responsive to deflection of said shock absorbing means for catching and holding said projectile when said projectile strikes and deflects said shock absorbing means, and electrical means for deenergizing said electromagnetic means to release said projectile.

2. In a radioactive source handling apparatus for propelling a radioactive source between a first and second position the combination which comprises a tube extending between said first and second position, a radioactive source positioned within said tube, pressure means far p pelling said radioactive source between said first and second position, means for Withdrawing said radioactive source from said second position, shock absorbing means for stopping said radioactive source in said second position, electromagnetic capturing means responsive to deflection of said shock absorbing means for holding said radioactive source in said second position when said radioactive source strikes and deflects said shock absorbing means, and electrical means for deenergizing said electro magnetic means to release said projectile.

3. In a capturing and shock absorbing device for catching a radioactive source having a magnetic probe thereon and propelled Within a tube the combination which comprises a source-receiving sleeve afiixed to an end of said tube, a cylindrical receiving chamber secured to said sieeve, an annular movable electromagnet positioned within said receiving chamber, spring means for yieldably holding said electromagnet in one position, said movable electromagnet having a bore therethrough extending along the longitudinal axis of said tube, said bore adapted to receive the magnetic probe on said radioactive source, a switch secured to said receiving chamber, said switch including a switch actuating arm extending into said receiving chamber and adapted to be activated by said annular movable electromagnet when said radioactive source strikes and moves said electromagnet against said spring means as said magnetic probe enters said bore, a source of voltage connected to said switch for energizing said electromagnet when said switch is operated whereby said electromagnetic probe is held within the bore of said electromagnet and said radioactive source is supported thereby, and means for deenergizing said electromagnet for releasing said probe and radioactive source.

4. Apparatus for capturing a propelled radioactive source travelling in a conduit and having a magnetic probe extending therefrom which comprises a movable springbiased electromagnet having an aperture therethrough mounted within said conduit, said aperture being designed to receive said magnetic probe extending from said radioactive source, and a movable spring-biased switch operating member extending through said aperture in said electromagnet for causing energization of said electromagnet when actuated by said radioactive source in entering the aperture in said electromagnet, whereby the magnetic attraction between said magnetic probe and said energized electromagnet retains the magnetic probe therein.

5. Apparatus for propelling and capturing a projectile which comprises a tube adapted to receive said projectile, a receiver secured to an end of said tube, said receiver including shock absorbing means and electromagnetic means for capturing said projectile, pneumatic means for propelling said projectile along said tube into said receiver, and electrical means for actuating said electromagnetic means to capture said projectile and for rendering said pneumatic means inoperative, said electrical means being responsive to said projectile striking said shock absorbing means.

6. Apparatus for propelling and capturing a projectile which comprises a tube adapted to receive said projectile; a receiver secured to said tube, said receiver including a movable electromagnet having an aperture therein for receiving a portion of said projectile, and shock absorbing means connected to said electromagnet; pneumatic means for propelling said projectile along said tube into said receiver whereby a portion of said projectile is received within said electromagnet and said projectile forces said electromagnet against said shock absorbing means; and electrical means for energizing said electromagnet and holding said projectile therein and for rendering said pneumatic means inoperative when said projectile moves said electromagnet against said shock absorbing means.

7. Apparatus for propelling and capturing a projectile which comprises a tube adapted to receive said projectile; a receiver having a chamber therein secured to an end of said tube; a slidable electromagnet mounted within said chamber, said electromagnet having a longitudinal bore therein; a first shock absorbing means connected to said electromagnet; a normally open switch mounted adjacent to said receiver, said switch including a switch actuating arm extending into said chamber, a switch contact plunger extending through said chamber and into said bore in said electromagnet; second shock absorbing means for biasing said switch contact plunger into said bore of said electromagnet and out of contact with said switch actuator arm; pneumatic means for propelling said projectile along said tube into said receiver whereby the kinetic energy of said projectile is absorbed by said first and second shock absorbing means, said projectile displacing said switch contact plunger from said bore in said electromagnet to operate said switch actuator arm and close said switch, and electrical means connected to said switch for energizing said electromagnet to hold said projectile therein and for rendering said pneumatic means inoperative.

References Cited in the file of this patent UNITED STATES PATENTS 2,269,458 Kahn Jan. 13, 1942 2,553,237 Camarero May 15, 1951 2,645,491 Valman July 14, 1953 2,965,761 Horvath Dec. 20, 1960 

1. A CAPTURING AND SHOCK ABSORBING DEVICE FOR CATCHING A PROJECTILE INCLUDING A RADIOACTIVE SOURCE THAT IS PROJECTED THROUGH A TUBE INTO A RECEIVING CASING WHICH COMPRISES SHOCK ABSORBING MEANS POSITIONED IN THE RECEIVING CASING IN THE PATH OF SAID PROJECTILE FOR RECEIVING AND STOPPING SAID PROJECTILE AT A POSITION DEPENDING ON THE CHARACTERISTICS OF THE SHOCK ABSORBING MEANS AND THE KINETIC ENERGY OF THE PROJECTILE, ELECTROMAGNETIC CAPTURING MEANS RESPONSIVE TO DEFLECTIN OF SAID SHOCK ABSORBING MEANS FOR CATCHING AND HOLDING SAID PROJECTILE WHEN SAID PROJECTILE STRIKES AND DEFLECTS SAID SHOCK ABSORBING 